Barrel for firing practice ammunition from automatic firearms



Nov. 19, 1968 R. GRONEMANN BARREL FOR FIRING PRACTICE AMMUNITION FROM AUTOMATIC FIREARMS Filed Nov. 28. 1966 AUTOMATlC RECOIL ELEMENTS AUTOMATIC In RECOIL ELEMENTS E INVENT OR RICHARD GRONEMANN ATTORNEYS United States Patent 3,411,229 BARREL FOR FIRING PRACTICE AMMUNITION FROM AUTOMATIC FIREARMS Richard Gronemann, Furth, Germany, assignor to Dynamit Nobel A.G., Troisdorf, Germany Filed Nov. 28, 1966, Ser. No. 597,271 Claims priority, application Germany, Nov. 26, 1965, D 48,760 4 Claims. (CI. 42-77) ABSTRACT OF THE DISCLOSURE The present disclosure relates to a barrel for shooting practice ammunition from automatic firearms. The barrel is subdivided into front and rear portions that are axially movable relative to each other. The rear portion is springloaded and contains the automatic recoil elements. With this arrangement, the relatively small recoil forces of the practice ammunition are sufficient to actuate the automatic recoil elements in the relatively low inertia rear portion.

Background of the invention The field of the present invention would include barrels for automatic firearms.

In the prior art, automatic firearms have be n fired with practice cartridges, for example, plastic training cartridges. When firing these practice cartridges from automatic firearms having a locking bolt, it was discovered that the relatively low propellant gas pressure of the practice cartridge, as compared to live cartridges, is insufficient to move the recoil elements of the firearm in the required manner. Therefore, when firing practice ammunition in automatic firearms, the automatic functioning of the firearm cannot be ensured with the prior art devices.

An attempt has been made to overcome this prior art deficiency by providing a recoil enhancing Venturi or Pitot tube in front of the mouth of the barrel. If it is possible to provide such tubes, they must be of relatively large size. Disadvantageously, the weight of the firearm is substantially increased; however, this cannot be tolerated in many cases. Furthermore, the required space cannot be tolerated in many firearms, for example, tanks.

It is also conventional to employ non-locking breach mechanisms, for example, the so-called mass lock. However, these devices do not lead to the desired success in many firearms, because they cannot always be provided in the firearm due to construction difficulties.

Also, it has been proposed to subdivide the barrel into two sections at a certain distance from the cartridge chamber. This division has been carried out in such a manner that the masses to be moved, that is, the rear portion of the barrel, including any bolt mechanisms, are adjusted in weight so that the automatic functioning of the firearm is insured when taking into consideration the relatively small gas pressures produced by the practice cartridge when fired. This division between the two portions provides a crack, which enlarges during firing when the two portions move relative to each other. During firing, the projectile must move over this crack so that it can be undesirably affected in regard to its guidance to produce a false trajectory. Also, with the widening of this crack, the groove inside of the barrel is divided into two portions that become offset with respect to each other in the different barrel portions.

Summary of the invention It is an object of the present invention to overcome the above-noted shortcomings in the prior art and to pro- Patented Nov. 19, 1968 vide a new, simple, and economical barrel to be used in firing practice ammunition from automatic firearms. In order to overcome the above-noted shortcomings of the prior art, the present invention divides the barrel of an automatic firearm to be used in firing practice ammunition into front and rear portions. Particularly advantageous results are obtained when the division is substantially flush with the cartridge case mouth of a practice cartridge inserted into the chamber. The front and rear portions are mounted to be axially displaceable with respect to each other, within certain limits, against a constantly effective bias force, for example, a spring. When the front and rear barrel portions have moved axially away from each other, an annular channel extending at least across a part of the barr l cross section is formed that is in communication with the bore of the barrel.

With the above-noted construction of the present invention, the propellant combustion gases are formed at the front end of the cartridge chamber under a relatively high pressure and travel a relatively short distance into the annular channel between the barrel portions; this relatively short travel distance assures a minimum of pressure reduction, which is advantageous because the pressure of the propellant gases is highest immediately adjacent the forward end of the cartridge case in the barrel. When the high pressure propellant gases enter the annular channel, they exert their pressure upon the front face of the rear barrel portion to thus urge the rear barrel portion rearwardly. By appropriately dimensioning the radial extension of the annular channel, it is possible to establish a front face of a predetermined size that will produce a sufficient recoil of the rear barrel section to ensure the automatic functioning of the locked components. When the practice cartridge is loaded into the cartridge chamber, the projectile is positioned in the transitional zone of the barrel, that is, directly adjacent the annular channel; when the cartridge is fired, the projectile is immediately provided with a barrel guidance that is perfect and not interrupted along its path at any point so that precise projectile guidance and projectile trajectory is ensured.

Brief description of the drawing Further objects, feature, and advantages of the present invention will appear from the following description of the accompanying drawing, in which:

FIGURE 1 is an axial cross-sectional view of the barrel according to an embodiment of the present invention before the projectile is fired; and

FIGURE 2 is a view similar to FIGURE 1, showing the barrel portions shortly after the cartridge has been fired.

Description of the preferred embodiment In the following description of the preferred embodiment, elements of conventional construction have been omitted from the drawing so that the description will be focused upon the new features of the present invention. It is to be understood that the front portion of the barrel may be of any conventional construction, the automatic recoil elements may be of any conventional form, and suitable mountings may be provided for all of the elements shown in the drawing.

In FIGURE 1, a cylindrical barrel front portion 1 is provided with a rearwardly facing cylindrical recess 6 for slidably receiving the forward cylindrical portion of a rear barrel stub or rear barrel portion 2. The front and rear barrel portions are provided with inter-engaging splines or the like (not shown) to provide relative axial movement only. The front barrel portion 1 forms the rear face and radial outer end, and the rear barrel portion 2 forms the front face of an annular channel 4. The front barrel portion is provided with a conventional bore for guiding a projectile. The rear barrel portion 2 is provided with a conventional cartridge chamber aligned with the bore. The projectile of a practice cartridge is indicated in its loaded position by broken lines at 5 in FIGURE 1. In its unfired, loaded position, the projectile 5 is already positioned in the rear end of the front barrel portion 1, that is, in the transition from the cartridge chamber to the groove and chase of the front barrel portion; the groove and chase not being in the drawing, because it is conventional. Conventional automatic recoil elements, for example, locking or bolting parts of the weapon, have been illustrated schematically at 3. These automatic recoil elements are securely mounted on the rear barrel portion 2 for rearward movement therewith. For purposes of illustration, it may be assumed that the front barrel portion 1 is rigidly mounted and the rear barrel portion 2 is free to slide relatively rearwardly a fixed distance. A spring 7, or the like, is provided to exert a constant forward resilient force on the rear barrel portion 2.

When the practice cartridge is fired, the propellant combustion gases enter into the annular channel 4 directly from the cartridge case forward edge. In this respect, the rear barrel portion is preferably constructed so that its forward face, that is, the front face of the annular channel 4, is axially flush with the forward-most edge of the practice cartridge case, as shown by the partial cross sectional view of the cartridge case in FIGURE 2, as determined by the forward abutment surface 8 of the rear barrel portion 2 for engaging the correspondingly shaped shoulder of the cartridge case. With very high pressure of propellant gases in the annular channel 4, the front barrel portion cannot move because it is rigidly mounted, but the rear barrel portion moves relatively rearwardly under the influence of the high pressure gases acting upon the front face of the rear barrel portion 2. In FIGURE 2, the cartridge has just been fired so that the projectile 5 has travelled a short distance forwardly in the bore of the front barrel portion 1, and the rear barrel portion 2 has moved rearwardly against the action of the spring 7 away from the front barrel portion 1. It is thus seen that the annular channel 4 will not interfere with the guidance of the projectile 5 and the relatively small inertia of the rear barrel portion 2 may be matched with the correspondingly relatively small gas pressure force of the practice cartridge so that the automatic recoil elements 3 will receive sufficient recoil for their automatic functioning.

Other embodiments of the present invention are contemplated within the above teachings. For example, instead of coupling the two barrel portions 1 and 2, as illustrated, in the manner of a socket joint, the annular slot 4 could be constructed so that it extends radially across the entire cross section of the barrel; with this modification, the two barrel portions 1 and 2 could be guided in a suitably provided sleeve that would preferably be attached to the front barrel portion 1, which sleeve would form the radially outer end wall of the annular channel 4.

The above embodiments have been shown and described only as examples of the present invention, and other modifications and embodiments are contemplated within the spirit and scope of the present invention as defined by the following claims.

I claim:

1. A barrel having a bore, having a cartridge chamber at its rear end and open at its front for shooting practice ammunition comprising a cartridge case from automatic firearms having spring-loaded automatic recoil elements wherein the improvement comprises: said barrel being subdivided (at the front end of the cartridge chamber) into a front portion and a rear portion mounted for limited axial displacement with respect to each other, said rear portion including said automatic recoil elements; bias means for providing a constantly effective bias force on said rear barrel portion toward said front barrel portion; said barrel portions having immediately adjacent front and rear faces forming an annular channel means in communication with said bore of said barrel and extending at least along a part of the barrel cross section for driving said rear barrel portion rearwardly against said bias means in response to gas pressure during burning of the cartridge propellant to operate the automatic recoil elements; said rear barrel portion having abutment means for engaging the practice cartridge case in its loaded position with the forwardmost end of the cartridge case flush with the front face and preventing forward movement relative to said rear portion.

2. The device of claim 1, wherein said bias means is a mechanical spring.

3. The device of claim 2, wherein said front barrel portion has a rearwardly opening substantially cylindrical recess and said rear barrel portion has a forwardly extending, complementarily formed projection slidably received within said recess; said front barrel portion having said rear face forming the forward end of said recess, and said rear barrel portion having said front face forming the front portion of said projection.

4. The device of claim 1, wherein said front barrel portion has a rearwardly opening, substantially cylindrical recess and said rear barrel portion has a forwardly extending, complementarily formed projection slidably received within said recess; said front barrel portion having said rear face forming the forward end of said recess, and said rear barrel portion having said front face forming the front portion of said projection.

References Cited UNITED STATES PATENTS 1,343,444 6/1920 Formby. 2,090,657 8/1937 Williams. 2,847,787 8/1958 Williams 42-76 2,992,596 7/1961 Hammer.

BENJAMIN A. BORCHELT, Primary Examiner. 

